I. Field
The present invention relates generally to communication, and more specifically to techniques for generating an identifier for a wireless device in a wireless communication network.
II. Background
Wireless devices such as cellular phones are widely used throughout the world for wireless communication. Each wireless device is typically assigned a globally unique equipment identifier that is embedded or inscribed into the wireless device by the manufacturer. The equipment identifier is used to identify the wireless device to a wireless network, for fraud detection, and for other purposes. The wireless device is also associated with a subscription identifier, which is an identifier used by the wireless network for the wireless device. The equipment identifier may be a serial number for the wireless device, and the subscription identifier may be a telephone number for the wireless device.
Electronic Serial Number (ESN) is one type of equipment identifier and is used for wireless devices in ANSI TIA/EIA 41 “Family of Standards”, which includes TIA/EIA-553 for Advanced Mobile Phone Service (AMPS), TIA/EIA-95 and TIA/EIA/IS-2000 for Code Division Multiple Access (CDMA), EIA/TIA-691 for Narrowband AMPS (NAMPS), and TIA/EIA-136 for Time Division Multiple Access (TDMA). ESN is a 32-bit number that is unique for each wireless device in TIA/EIA 41. Because of its relatively small 32-bit size, all of the available ESNs are expected to be exhausted in the year 2005. The use of ESN in CDMA is described in various documents for IS-2000 Releases 0, A, B and C, which are publicly available.
Mobile Equipment Identifier (MEID) is a new type of equipment identifier and is slated to replace ESN. MEID is a 56-bit number that is unique for each wireless device. MEIDs may be assigned to new wireless devices for AMPS, CDMA, TDMA, and other systems. The use of MEID in CDMA is described in various documents for IS-2000 Release D, which are publicly available.
In CDMA, an ESN is used in its entirety to generate a 42-bit Public Long Code Mask (PLCM), which is then used for wireless communication. Because ESNs are unique for all wireless devices assigned with ESNs, PLCMs generated based on ESNs are also unique. Unique PLCMs are important to ensure that communications for different wireless devices can be received and that these communications will not be overheard by unauthorized listeners.
IS-2000 Release D describes a method for generating a pseudo-ESN (pESN) based on an MEID and then generating a PLCM based on the pESN. The mapping from the MEID to the pESN is not unique. Hence, it is possible for two wireless devices with different MEIDs to map to the same pESN. Such an event is called a collision. Multiple wireless devices would have the same PLCMs whenever a collision occurs. Privacy may be compromised and other detrimental effects may also occur as a result of the collision.
There is therefore a need in the art for techniques to generate unique identifiers for wireless devices.